Sometimes users get a white screen after uploading an image. It looks like the images wasn't uploaded, because there is no mail and no entry in the dashboard.
Using the same image as the user I can reproduce the issue. If I upload the photo directly to Commons, there is no issue.
Originally reported in: https://github.com/wmnl/wikiportrait/issues/85
Hard to reproduce, so if the issue occurs, first the error log needs to be checked on the server.